Electron discharge tube having an improved electrode mounting structure



J. F. STEPHENS ELECTRON DISCHARGE TUBE HAVI May 16, 1967 NG AN IMPROVED ELECTRODE MOUNTING STRUCTURE 2 Sheets-Sheet 1 Filed July 25 1962 sfl Jw u a I...

INVEN TOR 2 JOE F. STEPHENS May 16, 1967 J. F. STEPHENS ELECTRON DISCHARGE TUBE HAVING AN IMPROVED ELECTRODE MOUNTING STRUCTURE 2 Sheets-Sheet 2 Filed July 23 1962 liiilhllliiiiliilllliliiliil FLG.5.

INVENTORZ JOE F. STEPHENS,

gywww HIS ATTORNEY.

United States Patent 3,320,463 ELECTRON DISCHARGE TUBE HAVING AN IMPROVED ELECTRODE MOUNT- ING STRUCTURE .l'oe F. Stephens, Owensboro, Ky., assignor to General Electric Company, a corporation of New York Filed July 23, 1962, Ser. No. 211,556 3 Claims. (Cl. 313-241) This invention relates to electron discharge tubes and, in particular, to novel and improved electrode mount structures therefor.

In electron discharge tubes, it is desirable to have an electrode mount structure that is rugged, easy to assemble, and inexpensive to manufacture. In addition, it is advantageous to provide for interchangeability of components, as for example, the electrodes and insulative supports, so as to facilitate the assembly of various tube types and to facilitate the derivation of various electrical characteristics of a given tube type, all during the process of manufacture.

Prior-art electron tubes have employed top and bottom insulative supports, or micas, and such tubes comprise a substantial proportion of commercially available tubes. Such tubes have utilized side rods to support and position the grid or control electrodes between the insulative supports, which resuit in obstruction of the current flow between cathode and anode. Automated assembly of tubes of this configuration is difficult and requires complex and expensive equipment. Shearing movement of one insulative support relative to the other results in variations in electrode spacing and grid misalignment, and hence adversely affect the electrical characteristic of the tube. In addition, modification of the electrical characteristics of a given tube cannot readily be effected during the process of manufacture but requires alteration of the size and shape of many elements of the electron tube. Prior art electron tubes are known having two spaced, vertically disposed, insulative supports Within the tube envelope, between which the various electrodes are positioned. However, these constructions have failed to provide the desired features of ruggedness and stability. The present invention eliminates the aforementioned problems inherentin the prior art electron tubes.

It is an object of the invention to provide an improved electron tube.

It is an object of the invention to provide an improved electrode mount structure for an electron tube.

It is an object of the invention to provide an electron tube which is rugged and easy to assemble and manufacture.

It is another object of the invention to provide an electrode mount structure for electron tubes, which facilitates the incorporation and shielding of a plurality of electron discharge devices within a single envelope.

It is a further object of the invention to provide an electrode mount structure for an electron tube which facilitates variation of tube type and alteration of the electrical characteristics of a given tube type by simply interchanging elements during the manufacturing process.

It is a further object of the invention to provide an improved electrode mount structure for an electron tube incorporating insulative supports which are disposed and arranged to facilitate assembly and which provide improved lateral and axial mechanical support within the tube envelope.

It is a further object of the invention to provide an improved electron tube and cathode structure therefor.

Briefly stated, in accordance with the illustrated embodiment of the invention, two spaced insulative supports are formed so that peripheral portions of the insulative supports contact the base, dome, and side wall portions of the electron tube envelope to provide axial and lateral support for the electrode mount structure within the envelope. A plurality of suitably formed and positioned apertures are provided in the insulative supports. Elec trodes, having ears extending from opposite edges thereof receivable in the apertures, are supported in spaced relation by and between the insulative supports. A doublecathode construction which has oppositely disposed and isolated emitting surfaces, is centrally positioned so that its longitudinal axis is parallel to the spaced insulative supports. The double cathode comprises two electrically independent sections having interleaved finger portions which serve as a heat shield and to retain a common filamentary heater within the chamber defined thereby. The mounting of appropriate electrodes on either side of the cathode between the insulative supports enables inclusion of two or more otherwise independent electron discharge devices within a single envelope. A shield electrode, surrounding the double cathode and mounted between the insulative supports, can be employed to isolate the respective electron discharge devices from each other, if desired or required. Additional shielding, mounted on the surface of the spaced insulative supports, maybe provided to reduce capacitive coupling between selected electrodes of the electron discharge devices, as desired or required.

The subject matter of the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is an isometric view of an electron tube incorporating the features of the invention;

FIG. 2 is an exploded perspective view of the electrodes incorporated in the electron tube of FIG. 1;

' FIG. 3 is a cross-sectional view of the electron tube of FIG. 1 taken along the line III-III thereof and illustrates the use of the electrode mount structure of the invention to incorporate two electron discharge devices within a single envelope;

FIG. 4 is an exploded, isometric view of the doublecathode construction of the invention drawn to an enlarged scale and FIG. 5 is a top plan view of the assembled double cathode of FIG. 4.

FIG. 1 illustrates an electron tube incorporating the Envelope 10 encloses spacedv features of the invention. insulative supports 12 and 13, which maybe of mica and which support the various electrodes of the tube and rnain tain them in spaced relation. Envelope 10 has a dome 15, a base or stem 16, and a side wall 17 connecting the dome and the base. Dashed line 18 defines the longi* tudinal axis of the electron tube.

In accordance with the invention, the insulative supports 12 and 13 are formed so that peripheral portions thereof contact portions of the interior surface of the envelope thereby to provide both axial and lateral support for the electrode mount structure within the envelope 10. To this end, trapezoidally shaped tabs 19, which extend from the main portions of supports 12 and 13, are adapted to have their edges contact the interior surface of the dome While the lower edges of the insulative supports 12 and 13 serve as pedestals Which rest on the interior surface of base 16. The contact of the trapezoidally-shaped tabs 19 with the dome 15 provides an accurate reference for positioning the electrode mount structure axially within the envelope and facilitates sealing. The contacting'portions of the trapezoidally-shaped tabs and the pedestals are shaped so as to conform to the surfaces of the envelope dome and base, respectively, thereby to ensure rigid axial support of the spaced insulative supports 12'and 13 within the tube envelope 10. Snubbers 21 project from the lateral edges of the insulative supports 12 and 13, contacting the envelope side walls 17 and rigidly positioning the insulative supports laterally within the envelope 10.

Further rigidity of the electrode mount structure of the invention is furnished by virtue of the cooperation of a ring-getter support 22 with trapezoidally-shaped tabs 19. Tabs 19 are notched on either side adjacent the main bodies of the insulative supports 12 and 13 so that the ring getter 22 may be slipped down the tapered sides of the tabs and snapped into the notches. Thus, the tabs 19 provide a convenient mount for a ring getter 22 and the ring getter, in turn, performs a clamping function to further stabilize the electrode mount structure of the invention. The ring getter arrangement, which is not part of the present invention, is further described and claimed in copending application No. 211,621, now Patent No. 3,197,546, filed concurrently herewith, of C. Hopper, Jr. and assigned to the assignee of the present invention.

The electrode mount structure of the invention may be arranged to incorporate one or more electron discharge devices within a single envelope. In addition, the electron discharge device or devices may be of any desired number of electrodes to provide diode, triode, tetrode, pentode, or any other desired type of operation. In the illustrative embodiment, the electrode mount structure of the invention incorporates two pentodes within the envelope 10. FIG. 2 shows somewhat more clearly, in the exploded perspective view, the double cathode construction that is utilized in the electron tube of the invention and the planar electrodes of one of the pentodes, namely, the part of the tube extending to the right of the cathode. It will be understood that the electrode arrangement extending to the left of the cathode can be similar, or, if desired, it can be different. Double cathode 30 is provided, at the top and bottom parts thereof, with ears 31 projecting from each side and in directions normal to the longitudinal axis 32 of the cathode. Ears 31 engage corresponding apertures in spaced insulative supports 12 and 13 (FIG. 1), the cooperation of ears 31 and the corresponding apertures providing support for the cathode 30 between insulative supports 12 and 13. The cathode structure of the invention is described in greater detail hereinbelow with reference to FIGS. 4 and 5.

A frame-type control grid 34 is positioned adjacent an electron emitting surface of cathode 30 by virtue of the insertion of ears 35, extending laterally from the longitudinal edges of control grid 34, in properly located apertures in insulative supports 12 and 13 (FIG. 1). Similarly, a frame-type screen grid 37, having ears 38 and a suppressor grid 40, having ears 41 are positioned in spaced relation between cathode 30 and anode 43, the latter having ears 44. Projections 42 and 42', formed at the top and bottom, respectively, of suppressor grid 40, operate to provide capacitive shielding between control grid 34 and anode 43. The positioning of the ears projecting from the various grids, the location of the apertures in the insulative supports 12 and 13, and the positioning of the lateral wires on the frame-type grids is coordinated so as to effect accurate alignment of the lateral grid wires of the control grid 34 and screen grid 37. As shown, the suppressor grid can be formed without lateral wires, if desired.

As previously noted, the electrode mount structure and the cathode of the invention may be employed to incorporate two electron discharge devices within a single envelope, as in the illustrated embodiment. In that event, the requisite electrodes are positioned on either side of the double cathode. If a dual electron discharge device arrangement is desired, a center shield 46, as shown in FIG. 2, is provided to electrostatically and electromagnetically shield the respective discharge devices from each other. Shield electrode 46 is formed with a window 47 and projections 48, here shown as two in number on each side edge of the shield. It will, of course, be understood that any suitable number of projections may be employed. Ears 49 engage apertures in the insulative supports 12 and 13 (FIG. 1) to mount the center shield 46 therebetween and projections 48 extend through slots in the insulative supports 12 and 13. The projections 48 function to provide optimum shielding effect between the mount structures on opposite sides of the cathode 30. Upon assembly, the cathode 30 is positioned within the window 47 of shield electrode 46 so that the plane of the shield projections 48 bisects the cathode structure. This arrangement furnishes improved shielding between the respective sections of the double cathode and between the respective control grids of the electron discharge devices.

The relative locations of the electrodes shown in FIG. 2 and the insulative supports 12 and 13, when the latter are disposed in supporting relation with respect to the electrodes, are shown more clearly in FIG. 3. To facilitate description, the reference numerals applied to the various electrodes of one of the pentodes, as shown in FIG. 2, are similarly applied, as primed numerals, to the corresponding electrodes of the other pentode. The mounting of the electrodes on the spaced insulative supports 12 and 13 is effected by virtue of the insertion of the ears, projecting from the longitudinal edges of the electrodes, into corresponding apertures in the spaced insulative supports. The spaced insulative supports serve to retain the various electrodes and maintain them in spaced relation within the envelope 10. Thus, cathode 30 is centrally located with ears 31 passing through apertures in insulative supports 12 and 13 so that the plane of cathode 30 is substantially normal to the planes of supports 12 and 13. The longitudinal axis 32 of the cathode is thus parallel to the planes of the supports 12 and 13. In the embodiment shown, the axis 18 of the tube coin cides with the axis 32 of the cathode, but the invention is not so limited. Control grids 34, 34', having ears 35, 35, screen grids 37, 37', having ears 38, 38', suppressor grids 40, 40', having ears 41, 41', and anodes 43, 43', having ears 44, 44, are mounted in substantially parallel planes on either side of cathode 30 to form two electron discharge devices, the ears of the respective electrodes passing through apertures in the insulative supports 12 and 13. Center shield electrode 46 surrounds cathode 30 and projections 48 extend through the spaced insulative supports 12 and 13 to increase the effective shielding between the respective electron discharge devices. The structure thus comprises a stacked array of electrodes supported in substantially parallel planes normal to the spaced insulative supports. The protrusion of the ears of the various electrodes and projections 48 of the central shield 46 through the spaced insulative supports 12 and 13 is also illustrated in FIG. 1.

The structure of the electron tube of the invention greatly facilitates variation in tube type or the electrical characteristics of a given tube type during the process of manufacture. Due to the uniformity of the dimensions of the electrodes, as shown in FIG. 2, variation of tube type is easily effected by adding or omitting electrodes, as desired, during manufacture, provision being made for appropriate apertures in the verticaly disposed, spaced, insulative supports. Similarly, spacing of electrodes can be easily changed to produce a desired variation of the electrical characteristics of a given tube.

The previously described rigid mounting of insulative supports 12 and 13 within envelope thus results in rigid positioning of the electrodes supported thereby and provides a rugged structure with resulting stable characteristics. The electrode mount structure of the invention minimizes the problem of grid misalignment experienced in conventional tube structures having top and bottom supports due to shearing movement of the cage.

Shield electrodes 23, 23, positioned on the exterior surfaces of insulative supports 12 and 13 respectively, have channels 29, 29' formed therein which correspond to and surround cars 44, 44' of anode electrodes 43, 43' projecting through the respective insulative supports. Shield electrodes 23, 23' are electrically connected to screen grid electrodes 37, 37' by virtue of being welded to cars 38, 38 and further mounting is effected by welding portions of shields 23, 23' to appropriate leads 24, 24' positioned adjacent thereto. Shields 23, 23' serve to electrostatically shield the anode electrodes 43, 43' from the control grids 34, 34. In general, the leads are welded, as shown at point 28 in FIG. 1, to appropriate ears of the various electrodes, which project through the insulative supports 12 and 13, to provide electrical connection thereto. As clearly illustrated in FIGS. 1 and 3, all welds are made on the side of the electrode mount structure, with none being made below, as required by prior art electron discharge devices. The accessibility of the welds, therefore, greatly facilitates assembly and manufacture of the electrode mount structure of the invention. As shown in FIG. 1, the leads are connected to pin connectors which project through the base 16 of envelope 10. Pin connectors 25 function to connect suitable sources of energizing potential, not shown, to the various electrodes.

The details of the structure of double cathode 30 are shown in FIGS. 4 and 5. As there illustrated, double cathode 30' comprises two cathode sections 50 and 51, each of the sections having long tabs or fingers 53 and short fingers 54 projecting from the respective longitudinal edges of the sections 50 and 51, normal to the planes of the sections, and alternately arranged along each longitudinal edge. Each of the cathode sections has an emitting surface 56 on the side opposite the direction in which the fingers 53 and 54 project. Ears 31 extend laterally from the tops and bottoms of the cathode sections in directions normal to the longitudinal axis 32 of the cathode 30. Ears 31 support double cathode 30 by engaging corresponding apertures in spaced insulative supports 12 and 13. An isometric view of the cathode structure, as assembled, is presented in FIG. 2.

FIG. 5 illustrates the positioning of a unitary filamentary heater 58 within the enclosure formed by the cathode sections 50 and 51 and the fingers 53 and 54 projecting therefrom. Long fingers 53 and short fingers 54 of the respective cathode sections intermesh but do not contact each other and serve to retain the strands of heater 58 within the enclosure. The cooperation of the long and short fingers also functions to minimize heat loss from the heater, thereby improving the over-all efficiency of the electron discharge devices, while permitting the respective cathode sections to be electrically independent. Thus the cathode sections 50 and 51 can be connected to separate pin connectors and may be operated at different potentials depending upon the requirements of the respective electron discharge devices.

Although the invention and its operation has been described with reference to specific embodiments, the invention is not limited to these embodiments. Many modifications within the spirit and scope of the invention will be obvious to those skilled in the art. For example, the electrode mount structure of the invention may be used in conjunction with a single electron discharge device and the type of electron discharge device is not limited to a pentode as shown. It is thus intended that this invention is not limited to the particular details shown and described which may be varied without departing from the spirit and scope of the invention in the appended claims.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An electron discharge device, comprising an envelope, a plurality of frame-type electrodes, a cathode, at least one ear extending laterally from each of the longitudinal edges of each of said electrodes and of said cathode, a pair of spaced insulative supports having peripheral portions in contact with the interior surface of said envelope, each of said pair of spaced insulative supports being formed with a plurality of apertures for receiving said ears to support said electrodes and said cathode in spaced relation between said pair of insulative supports, said ears and said apertures being arranged in a predetermined pattern to ensure the longitudinal axis of said cathode being parallel to the plane of each of said pair of insulative supports, and shield electrodes each having a channel formed therein positioned on the outside surfaces of each of said pair of spaced insulative supports with the channels enclosing corresponding ears of an electrode projecting through said insulative supports for minimizing capacitive coupling between electrodes.

2. An electron tube, comprising an envelope, a pair of spaced insulative supports having peripheral portions in contact with the interior surface of said envelope, a cathode electrode supported between said pair of spaced insulative supports with the longitudinal axis of said cathode parallel to the plane of each of said pair of spaced insulative supports, a first group of electrodes supported between said pair of spaced insulative supports on one side of said cathode to form therewith a first electron discharge device, a second group of electrodes supported between said pair of spaced insulative supports on the opposite side of said cathode from said first group of electrodes to form therewith a second electron discharge device, and a shield electrode mounted between said pair of spaced insulative supports and having projections extending through said pair of spaced insulative supports in a plane within said cathode to provide shielding between said first and said second electron discharge devices.

3. An electron tube, comprising an envelope having a dome, a base, and a side wall connecting said dome and said base, a pair of spaced insulative supports each having a top portion in contact with said dome, a bottom portion in contact with said base, and lateral edge portrons 1n contact with said side wall of said envelope, a plurality of electrodes, at least one ear extending laterally from each of the longitudinal edges of each of said electrodes and through apertures formed in each of said pair of spaced insulative supports receiving said ears to support said electrodes in spaced relation between said pair of insulative supports, said plurality of electrodes including a cathode electrode comprising twoelectrically independent sections heated by a common filamentary heater and having its longitudinal axis parallel to the plane of each of said pair of insulative supports, a first group comprising at least one electrode positioned on one side of said cathode to form therewith a first electron discharge device, a second group comprising at least one electrode positioned on the opposite side of said cathode from said first group to form therewith a second electron discharge device, a plurality of electrical leads connected to appropriate ears to provide energizing potentials to said electrodes, a shield electrode mounted between said pair of spaced insulative supports having projections extending through said spaced insulative supports in a plane Which bisects said cathode to provide shielding between said first and said second electron discharge devices, and shield electrodes each having a channel formed therein mounted on the exterior surfaces of each of said pair of spaced insulative supports with the channels enclosing corresponding ears of an electrode projecting through said insulative supports for minimizing capacitive coupling between electrodes.

References Cited by the Examiner UNITED STATES PATENTS 1,671,598 5/1928 Mavrogenis 3131 2,166,744 7/1939 Seelen et al. 25027.5 2,250,874 7/1941 McCarty 313338 X 8 2,366,320 1/1945 Elston 250-275 2,428,020 9/1947 Goodchild et al. 313-254 2,745,981 5/1956 Sanabria et al 313254 2,841,734 7/ 1958 Horton et al 31324O 2,862,136 11/1958 Miller 313261 2,937,301 5/1960 Germeshausen et al. 313--338 X 3,010,046 11/1961 Dailey et al. 313346 3,113,236 12/1963 Lemmens et al. 313-346 JOHN W. HUCKERT, Primary Examiner.

DAVID J. GALVIN, JAMES D. KALLAM, Examiners.

D. O. KRAFT, D. E. PITCHENIK, C. E. PUGH, A. J.

JAMES, Assistant Examiners. 

1. AN ELECTRON DISCHARGE DEVICE, COMPRISING AN ENVELOPE, A PLURALITY OF FRAME-TYPE ELECTRODES, A CATHODE, AT LEAST ONE EAR EXTENDING LATERALLY FROM EACH OF THE LONGITUDINAL EDGES OF EACH OF SAID ELECTRODES AND OF SAID CATHODE, A PAIR OF SPACED INSULATIVE SUPPORTS HAVING PERIPHERAL PORTIONS IN CONTACT WITH THE INTERIOR SURFACE OF SAID ENVELOPE, EACH OF SAID PAIR OF SPACED INSULATIVE SUPPORTS BEING FORMED WITH A PLURALITY OF APERTURES FOR RECEIVING SAID EARS TO SUPPORT SAID ELECTRODES AND SAID CATHODE IN SPACED RELATION BETWEEN SAID PAIR OF INSULATIVE SUPPORTS, SAID EARS AND SAID APERTURES BEING ARRANGED IN A PREDETERMINED PATTERN TO ENSURE THE LONGITUDINAL AXIS OF SAID CATHODE BEING PARALLEL TO THE PLANE OF EACH OF SAID PAIR OF INSULATIVE SUPPORTS, AND SHIELD ELECTRODES EACH HAVING A CHANNEL FORMED THEREIN POSITIONED ON THE OUTSIDE SURFACES OF EACH OF SAID PAIR OF SPACED INSULATIVE SUPPORTS WITH THE CHANNELS ENCLOSING CORRESPONDING EARS OF AN ELECTRODE PROJECTING THROUGH SAID INSULATIVE SUPPORTS FOR MINIMIZING CAPACITIVE COUPLING BETWEEN ELECTRODES. 